1. Field of the Invention
The present invention relates to an alpine ski boot for releasable attachment to an alpine ski. In particular, it relates to an alpine ski boot articulated to facilitate comfort, safety and wearability of the boot both on the ski for skiing and off the ski for walking.
2. Description of Related Art
Presently, ski boots for alpine skiing are generally of a construction having a rigid plastic upper and a rigid boot sole. This construction is preferred for several reasons. For alpine ski boots, it is believed that a rigid boot sole is advantageous when used with contemporary quick-release bindings, particularly bindings of the type that engage an extension of the toe end of the rigid sole and an extension of the heel end of the rigid sole. Quick-release bindings generally have spring loaded mechanisms that allow a user to easily attach a ski by placing the extension of the toe end of a booted foot into a front part of the automatic binding and then stepping down on the boot heel to engage the extension of the heel end of the boot in a rear part of the binding to lock the boot to the ski in a clamping engagement. The boot is easily releasable from the binding by a trigger mechanism selectively activated by the user with a pole or an opposite foot. Generally, the quick-release bindings are also adapted to release the rigid boot sole automatically at a predetermined setting in extraordinary loading situations, such as during an unplanned or accidental fall, allowing the skier""s booted foot to separate from the ski, thus reducing the risk of the ski causing injury to the skier.
The binding firmly clamps the rigid boot sole to the ski, so that, under ordinary skiing conditions, the ski boot, and thus the skier""s foot inside the ski boot are held firmly with respect to the ski attached to the binding. The firm hold of the skier""s foot with respect to the ski is essential to facilitate the skier""s ability to control the orientation of the skis with respect to the surface being traversed, e.g., mountain slopes, and thereby, to safely control the direction and speed of travel on those surfaces. All alpine safety bindings conform to DIN standards which require exacting sole dimensions to activate properly. In addition, the newer shaped alpine skis have increasingly gained both popularity and a larger market share. These newer shaped skis are steered differently by the skier than prior alpine skis which had straight sides. More specifically, there is a greater emphasis on ankle angulation to turn the ski. This angulation of the ankle within a rigid boot structure conveys this body movement to the skis. To boost the affect of angulation, most skis and/or bindings are fitted with lifts to increase the leverage of angulation. This increases the need for a very rigid boot structure to avoid accidental binding release during sudden or high-speed maneuvers.
In alpine skiing, rigid uppers are preferred because they are known to prevent the foot and ankle injuries common to skiers using an earlier style of boot and binding, namely leather boots with flexible uppers received in fixed non-automatic bindings. In an accident, the earlier style of boot and binding afforded little or no support or protection to foot and ankle bones against twisting into unnatural positions due to the lever arm effect of a long ski unyieldingly attached to the foot. Thus, these bones were susceptible to injury or breakage. Rigid uppers substantially eliminate the likelihood of injury to the foot or ankle. These uppers generally extend well above the ankle and are adapted to be tightly fastened about the foot and ankle to restrict movement of the foot and flexibility of the ankle with respect to the ski and the lower leg.
By restricting movement of the foot and flexibility of the ankle with respect to the lower leg, rigid uppers combined with rigid soles are also known to provide a rigid link-up between a skier""s foot and leg, which allows the skier to properly shift and direct body weight to the skis and to effect greater control of the orientation and direction of the skis. Turning, which determines both the speed and direction of travel, is easier with rigid uppers and rigid soles. Skis have substantially parallel sides that cause the skis to travel in a straight line, and resist turning. To overcome this bias towards straight line travel, skis generally require a weight shift towards the front of the ski (i.e., xe2x80x9cforward loadingxe2x80x9d) to bend a forward part of the ski sufficiently to induce the ski to carve a turn in the desired direction. It is believed that rigid uppers combined with rigid soles better accomplish this forward loading by restricting movement of the foot and ankle relative to the lower leg, and by holding the foot such that it is pitched or angled forward slightly causing the skier to assume a posture with knees slightly bent. Thus, boots with rigid soles and rigid uppers exhibit several advantages preferred by alpine skiers.
Boots with rigid uppers and rigid soles also have a significant disadvantage in that they are cumbersome and difficult to walk in when released from the skis. While skiing, a skier wearing a pair of boots each with a rigid sole and rigid upper has significantly enhanced control and maneuverability due to the rigid construction of the boots which firmly position the foot with respect to the ski. However, once released from the skis, the mobility and maneuverability of the wearer is severely handicapped by the rigid upper and the rigid sole. Maneuvering about a ski area with the skis removed from the boots, such as, for example, maneuvering in the ski lodge, or to and from a locker or a vehicle, requires extra effort and agility on the part of the wearer. Because the toes are not free to flex with respect to the rest of the foot, and because the foot is not free to flex with respect to the leg, the rigid upper and the rigid sole make walking on level, dry surfaces difficult, while traversing slopes and staircases is particularly hazardous. The slippery conditions caused by ice, melting snow and mud commonly found both outside and inside ski facilities compound the maneuverability problems associated with walking in ski boots having rigid uppers and rigid soles, and may result in falls and injuries. It is not uncommon to see skiers of various ages and skill levels flailing their arms in an attempt to regain their balance off the skis because ski boots with rigid uppers and rigid soles do not permit movement of the toes, foot and ankle in a natural manner.
U.S. Pat. Nos. 5,026,087, 5,020,822 and 4,880,251, all to Wulf et al., disclose a ski boot having a boot upper, i.e., a foot shell formed of two rigid segments attached to a sole. The segments of the foot shell overlap in sliding engagement so that a living hinge is created in the integral sole at approximately the location of the ball of the foot within the boot. To make the sole rigid for use on a ski, the fulcruming of the living hinge is eliminated by locking the overlapping segments of the foot shell together, thus forming what is essentially a rigid upper from the two segments. The sole therefore derives its rigidity from the foot shell. In addition, the boot disclosed by Wulf et al., is attached to a ski by way of a binding connected to a rear portion of the sole only, i.e., the boot is not attached by a toe end of the sole, thus shortening the length of the portion of the sole attached in the binding and correspondingly reducing the lever arm advantage of the sole in turning the ski.
U.S. Pat. No. 5,572,806 to Osawa discloses a flexible ski boot with an upper having a flexible portion behind the toe and a sole having a rigid toe portion connected by a hinge to a rigid heel portion. When the boot is received in a binding, a mechanism incorporated in the sole is activated to extend a bar-like member from a clearance in the toe portion into a hole in the heel portion to lock the toe portion of the sole in alignment with the heel portion of the sole. However, the disclosure indicates that even when the boot is attached to a ski, the boot upper has a degree of flexibility when the ski is subjected to stresses. Since the boot upper is connected to the ski by way of the sole, this would imply that the sole also has a degree of flexibility when attached to the ski. In the disclosure, this is viewed as an advantage because the boot upper is less susceptible to cracking when the ski is on uneven surfaces. However, while a boot with an upper or sole having a small degree of flexibility may be suitable for typical recreational use, it would almost certainly be unsuitable for competitive or extreme recreational use where precise control of the ski is essential. The disclosure also does not address an arrangement typical of contemporary boot and binding combinations, i.e., bindings having a toe pad and heel pad that elevate the bottom surface of the boot sole from the top surface of the ski such that the middle portion of the sole is unsupported. For a one piece rigid sole, an unsupported middle portion is not a problem. However, with a hinged two-part sole, the unsupported middle portion of the sole tends to flex toward the top surface of the ski, which could in turn cause premature or undesired release of the boot from the binding.
Another disadvantage of conventional alpine ski boots is that the boots unsatisfactorily bind the forefront, ankle, and shin securely to the rigid shell. As previously mentioned, such binding is desirable because it immediately conveys skier movements from the boots to the skis. Typically, alpine ski boots contain a soft bladder or inner boot which encases the skier""s foot. In an effort to more solidly bind the foot, ski boot manufacturers have attempted to secure the foot inside the bladder to the rigid shell by compressing the overlapping shell against the bladder by means of ratcheting buckles. Because people have a wide variety of foot shapes (e.g., thin, wide, high insteps, flat, etc.), it is difficult to ratchet the rigid plastic shell against the inner bladder and such action often causes discomfort to the skier. For example, over-ratcheting of the shell often results in a cut off in circulation to the foot, thereby causing the skier to get cold feet. Furthermore, heel lift from inside the rigid boot floor is detrimental to properly guiding the skis and is common in all ski boots having rigid shells. Ski boot manufacturers have dealt poorly with the problem of heel lift inside the boot by designing the inner bladder to tightly compress against the ankle, thereby causing discomfort and other problems. To prevent heel lift, some skiers resort to buckling their boots so tightly as to cut off circulation.
Most conventional alpine ski boots are front entry boots having an overlapping plastic flange on the forefoot thereof. This overlapping flange is pulled together by external ratchet straps. This overlap makes boot entry difficult as the foot must spread one flange section away from another flange section. Because of their rigidity, the flange sections try to retain their original shapes and this makes it difficult for the skier to place his/her foot in the boot.
Accordingly, it was previously thought that, in order to properly interact with an alpine ski binding that engages the toe end and the heel end of a sole, for entry and release manually or automatically, a boot sole must be completely rigid from heel to toe; and in order to provide the stiff up-link between a skier""s foot and leg preferred for proper control of a ski while skiing, a boot upper and boot sole combination must be substantially rigid from heel to toe and from sole to ankle cuff. However, this construction suffers from the aforementioned disadvantages as well as others.
Thus, there is a need for an alpine ski boot that will properly interact with a ski binding that engages a toe end and a heel end of a sole, that provides a rigid up-link from the skier""s foot to the skier""s leg, while facilitating comfort, mobility and maneuverability not only on the ski but off the ski as well, as well as overcoming the other above-mentioned disadvantages associated with conventional alpine skis.
According to the present invention, a ski boot is presented and includes a segmented boot upper attached to a two part rigid foot bed member. The foot bed member has a rigid first portion corresponding to a toe part of the foot, and a rigid second portion corresponding to the arch and heel parts of the foot. The first portion is hinged to the second portion at approximately the location of the ball of the foot within the boot. The boot upper has a rigid toe portion connected to the first portion of the foot bed member and a rigid heel portion connected to the second portion of the foot bed member. A wedge-shaped gap is provided between the toe portion and the heel portion of the upper to permit the first portion of the foot bed member to pivot with respect to the second portion. The boot is provided with a stop means such that one portion of the hinged sole may pivot above a plane passing through the other portion, but may not pivot below that plane.
When the hinged sole is received in an alpine ski binding which engages portions of the toe and heel of the boot, the first and second portions of the foot bed member are aligned in a single plane. In this position, the foot bed member act as a unitary, rigid member. The ski boot further includes a selectively locking articulated truss assembly which extends across the wedge-shaped gap and serves to lock the toe portion of the boot upper to the heel portion thereof. One end of the truss assembly is attached to the toe portion, while the other end is the end which selectively locks with a truss locking section of the heel portion. The truss assembly includes a knob which permits the user to lock or unlock the truss assembly. When the user desires for the toe portion to be able to pivot relative to the heel portion, as in the case of walking, the user simply unlocks the truss assembly from the heel portion, thereby permitting the toe and heel portions to pivot about the hinged foot bed member. In skiing mode, the truss assembly is in a locked position.
The ski boot also includes internal/external adjustable straps which are disposed at least partially between an inner boot bladder and the hard shell of the ski boot. These straps overcome the difficulties in properly fitting the rigid shell to the skier""s foot. The two straps are anchored inside of the rigid boot cavity to the floor of the foot bed member. One strap passes over the top of the inner bladder at the forefoot location and the other strap passes over the top of the bladder at the ankle bend of the foot. Each strap is coupled to a respective thumbscrew device which is coupled to the boot upper. The thumbscrew devices are designed so that the user may rotate handles thereof to cause the straps to be tightened. To loosen the straps, the user moves a lever of the thumbscrew device which causes the strap to be freely loosened. Pressing the hard shell against the inner bladder is eliminated at the forefront and ankle and positive hold down of the forefoot and heel is achieved. This improves comfort and performance is enhanced by providing instant feedback of steering motions to the hard shell of the boot and hence to the skis.
Other features and advantages of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.